The standard is not clear. For me the drop to <0.1 was a six week deal, but I am not the norm. Because I had advanced disease I was tested three weeks out, then 5 then 6 and have had 7 tests since my surgery in February. Some I requested some scheduled. I was able to follow my drop from 13.7 pre-operative to undetectable. At my peak I was originally tested at 19.8. The next week it was 18.7, then the 13.7 just before biopsy. These are vast ranges and I wanted to know more about my physiological behavior. So I asked for the tests. And to be honest, I don't think Walsh is wrong and he is quoting the standard. My Oncologist does not agree with Walsh on this one. He tested right out of the gate. He stated that a drop of 50% per day was what he expected. But I have seen other posters here not drop that quickly, including myself. Here's how those tests went:

October 3, 2006: 19.8October 10, 2006: 18.7Biopsy December 12 (3+4=7 4 of 8 positive up to 80%)Surgery February 16,2007March 12, 2007: 0.9March 18, 2007: 0.1March 25, 2007: <0.1Tests in April, May, July, and September have all been <0.1

Looking at my histogram, I was ably to determine that I was a 30% per drop after surgery. I am also lucky to have my advanced disease get down to zeros. Walsh was right but so was my oncologist. Six weeks is enough time and 3 months will be accurate.